Refrigerant Piping Installation; Caution - Mitsubishi Electric CITY MULTI PQRY-P250 Installationshandbuch

7. Refrigerant piping installation

City Multi WR2 Series is constituted by an end branching system in which the refrigerant piping from heat source unit is branched at BC controller and
connected to each indoor unit.
The connection method adapted is flange connection for low pressure pipe and flare connection for high pressure pipe between heat source unit and
BC controller, and flare connection between BC controller and indoor unit. Brazing connection is employed for joint pipe set and branch pipe set.
Warning:
Always use extreme care to prevent the refrigerant gas (R407C) from leaking while using fire or flame. If the refrigerant gas comes in contact
with the flame from any source, such as a gas stove, it breaks down and generates a poisonous gas which can cause gas poisoning. Never
weld in an unventilated room. Always conduct an inspection for gas leakage after installation of the refrigerant piping has been completed.

7.1. Caution

1 Use the following materials for refrigeration piping.
• Material: Use refrigerant piping made of **C1220 phosphorus deoxidized copper as specified in the *JIS H3300 "Copper and copper alloy
seamless pipes and tubes". In addition, be sure that the inner and outer surfaces of the pipes are clean and free of hazardous sulphur, oxides,
dust/dirt, shaving particles, oils, moisture, or any other contaminant.
• Size: Refer to Pages 10 to 11 .
2 Commercially available piping often contains dust and other materials. Always blow it clean with a dry inert gas.
3 Use care to prevent dust, water or other contaminants from entering the piping during installation.
4 Reduce the number of bending portions as much as possible, and make bending radius as big as possible.
5 Always observe the restrictions on the refrigerant piping (such as rated length, the difference between high/low pressures, and piping diameter).
Failure to do so can result in equipment failure or a decline in heating/cooling performance.
6 The City Multi Series WR2 will stop due an abnormality due to excessive or insufficient coolant. At such a time, always properly charge the unit.
When servicing, always check the notes concerning pipe length and amount of additional refrigerant at both locations, the refrigerant volume
calculation table on the back of the service panel and the additional refrigerant section on the labels for the combined number of indoor units. (Refer
to Pages 10 to 11 .)
7 Use liquid refrigerant to fill the system.
8 Never use refrigerant to perform an air purge. Always evacuate using a vacuum pump.
9 Always insulate the piping properly. Insufficient insulation will result in a decline in heating/cooling performance, water drops from condensation and
other such problems. (Refer to Pages 15 to 16 .)
0 When connecting the refrigerant piping, make sure the ball valve of the heat source unit is completely closed (the factory setting) and do not operate
it until the refrigerant piping for the heat source and indoor units has been connected, a refrigerant leakage test has been performed and the
evacuation process has been completed.
A Always use a non-oxidizing brazing material for brazing the parts. If a non-oxidizing brazing material is not used, it could cause clogging or damage
to the compressor unit. (Details of the piping connections and valve operation can be found on Pages 12 to 13 .)
Warning :
When installing and moving the unit, do not charge it with refrigerant other than the refrigerant (R407C) specified on the unit.
- Mixing of a different refrigerant, air, etc. may cause the refrigerant cycle to malfunction and result in severe damage.
Caution:
• Use refrigerant piping made of **C1220 phosphorus deoxidized copper as specified in the *JIS H3300 "Copper and copper alloy seamless
pipes and tubes". In addition, be sure that the inner and outer surfaces of the pipes are clean and free of hazardous sulphur, oxides, dust/
dirt, shaving particles, oils, moisture, or any other contaminant.
- Contaminants on the inside of the refrigerant piping may cause the refrigerant residual oil to deteriorate.
• Use liquid refrigerant for sealing.
- Sealing with gas refrigerant will change the composition of the refrigerant in the cylinder and reduce the unit's performance.
• Never use existing refrigerant piping.
- The large amount of chlorine in conventional refrigerant and refrigerator oil in the existing piping will cause the new refrigerant to deteriorate.
• Store the piping to be used during installation indoors and keep both ends of the piping sealed until just before brazing.
- If dust, dirt, or water gets into the refrigerant cycle, the oil will deteriorate and the compressor may fail.
• Do not use a charging cylinder.
- Using a charging cylinder may cause the refrigerant to deteriorate.
* Japanese industrial standard.
** Comparable to CU-DHP (CUPROCLIMA), Cu-bl (AFNOR), C12200 (ASTN), SF-Cu (DIN)
9